1. Field
The present disclosure is directed to waveguide structures, and in particular, to an apparatus and method for detecting optical radiation.
2. Related Art
Waveguide-based integrated optics in silicon (see reference [1], incorporated herein by reference in its entirety) provides an ideal platform for concentrating and guiding light at the nanoscale. The high index contrast between silicon and common cladding materials enables extremely compact waveguides with very high mode field concentrations, and allows the use of established CMOS fabrication techniques to define photonic integrated circuits (see references [2-4], incorporated herein by reference in their entirety).
It has recently become possible, by using slotted waveguides (see reference [5], incorporated herein by reference in its entirety), to further concentrate a large fraction of the guided mode into a gap within the center of a silicon waveguide. This geometry greatly magnifies the electric field associated with the optical mode, resulting in electric fields in excess of 106 V/m for continuous-wave, sub-millitwatt optical signals. Moreover, since the slotted geometry consists of two silicon strips which can be electrically isolated, a convenient mechanism for electro-optic interaction is provided. Such waveguides can be fabricated with low loss; the applicants have previously demonstrated −10 dB/cm (see reference [6], incorporated herein by reference in its entirety).